If the Greeks in philosophy and science were authoritative guides, if in art and literature they were unapproachable, if the Roman republic, as Machiavelli thought, was an ideal state, it would seem that the powers of Nature had declined, and she could no longer produce the same quality of brain.

So long as this paralysing theory prevailed, it is manifest that the idea of Progress could not appear.
But in the course of the sixteenth century men began here and there, somewhat timidly and tentatively, to rebel against the tyranny of antiquity, or rather to prepare the way for the open rebellion which was to break out in the seventeenth.

Breaches were made in the proud citadel of ancient learning.

Copernicus undermined the authority of Ptolemy and his predecessors; the anatomical researches of Vesalius injured the prestige of Galen; and Aristotle was attacked on many sides by men like Telesio, Cardan, Ramus, and Bruno.

[Footnote: It has been observed that the thinkers who were rebelling against the authority of Aristotle--the most dangerous of the ancient philosophers, because he was so closely associated with theological scholasticism and was supported by the Church--frequently attacked under the standard of some other ancient master; e.g.Telesio resorted to Parmenides, Justus Lipsius to the Stoics, and Bruno is under the influence of Plotinus and Plato (Bouillier, La Philosophie cartesienne, vol.i.p.